1. Field of the Invention
The present invention relates to a sheet finisher which can appropriately fold, sort, fasten and collect sheets which have come out of a copy machine and the like.
2. Description of the Prior Art
Japanese Patent Application Laid-Open No. 61-211272 (1986) discloses a previously proposed sheet finishing device.
This device is arranged to take the sheets which have come out of a copy machine, fold the same and then eject them onto an upper tray. Following this, the sheets on the upper tray are induced to engage a stopper and become aligned. They are then fastened together by stapling. After this fastening operation, the stopper is rotated and the fastened stack of sheets is collected by being dropped onto a lower tray. In this device the lower tray is arranged at a predetermined inclined or slanted angle.
However, with this prior art arrangement, as the stacks of sheets which are fastened together are induced to drop onto the lower tray under the influence of the stopper rotation only, the assuredness with which the sheets are unfailingly dropped into the intended position is low. That is to say, if the upper tray is formed of normal types of plastic, the effect of friction and static electrical charges hinders the sliding of the sheets.
In order to overcome the effect of the friction and static electricity, if the angle of the upper tray is overly increased, the capacity of the tray is undesirably reduced.
Further, if lower tray angle is fixed the capacity of the same is limited.
In particular, if a Z folding mode is selected, the folds of the Z folded sheet cause the thickness of the stack to become three times greater than normal. Depending on the number of stacks accumulated on the lower tray, the entry angle which is defined by a vertical line and the lower tray, rapidly becomes reduced.
Under these conditions, in the worst case, as the stack of sheets is dropped, the leading edge of the stack strikes against those already received in the tray and results in spillage.
Normally, with the so called Z sheet folding function, the sheets which are required to be folded in the folding device, are half folded and the half folded sheets are then again folded in half.
A prior art device which features this Z folding function is disclosed in Japanese Patent Application Laid-Open No. 61-217476 (1986).
In this arrangement a sheet folding transfer chute and a sheet transit chute having a pair of discharge rollers are provided at the downstream of an entrance deflector which is switched in accordance with the presence or absence of the demand for folding.
A first deflector is interposed at the downstream end of this sheet folding transfer chute, and first and second folding rollers which constitute a pair of folding rollers of a first folding stage and a folding position control guide chute are also provided.
Further, a second deflector is interposed downstream of the folding rollers of the first folding stage and second and third folding rollers which constitute a second folding stage roller pair and a second folding position control guide chute are provided.
Additionally, a third deflector is interposed downstream of the second folding stage roller pair, and third and fourth folding rollers which constitute a third folding stage roller pair and a third folding position control guide chute are provided.
Downstream of the roller pair of the third folding stage, a final guide chute is provided which merges with the above mentioned transit chute at its end.
A discharge roller is provided at the downstream of the final guide chute and the transit chute and arranged to discharge the treated sheets through an ejection opening onto a tray.
However, with this type of folding device when forming the folds in the sheets, as the sheet folding position control guide chute which receives the leading end of the sheet subjects the sheet to a degree of resistance, the bowing of the central portion of the sheet which is pinched by the folding rollers is reduced, and in addition to this during the half and Z folding modes, for example, depending on the size of the sheet, first to third sets of folding rollers are necessary in addition to the sheet folding position control guide chute. Accordingly, the construction of the finisher becomes complex, expensive and cannot be rendered compact.
Further, as the discharge rollers and the tray are fixed in place, it is not possible for example, to continuously Z fold a large number of sheets. That is to say, as the thickness of the folded and unfolded ends of the Z folded sheets is notably different, as the number of sheets increases the upper surface of the stacked sheets rapidly becomes inclinded with respect to the surface of the tray.
Under these conditions the accumulative capacity of the device is lowered and the manner in which the sheets are discharged and pushed out onto the tray deteriorates the stacking neatness.
Further, the sheet folding mechanism is required to include a half folding mode which folds the sheets in half, a Z folding mode which folds the sheets and then folds the folded section again, in addition to a non-folding mode.
With this above mentioned prior art arrangement irrespective of the sheet folding mode the sheets which have been processed are discharged at a predetermined height above the tray. As the thickness of the folded sheets is two to three times that of the non-folded ones, in order to increase the accumulative capacity, it has been proposed to increase the distance between the top of the tray and the sheet discharge means.
However, this measure leads to the problem that, particularly during the non folding mode, the mass per unit area of the sheet is relatively small and the neatness with which the sheets are stacked is reduced. That is to say, the layer of air between the sheet being discharged and the surface onto which the sheet is intended to drop, produces a floating effect which deteriorates the neatness with which the sheets pile one on the other.
Normally, sheet finishers are provided with a fastening device which staples the collected stack of sheets together. While this appears to be desirable at first glance, before the sheets can be appropriately stapled they must have their side and top edges aligned.
In order to achieve this alignment or setting, one prior proposed arrangement has provided the tray with two side edges and base section and has utilizes the weight of the sheet in combination therewith to define means for suitably aligning the sheets in a suitably neat manner.
An alternative arrangement has provided one fixed side edge, a base and has added an adjustable guide which pushed sideways toward the single fixed edge in order to improve the neatness of the sheet stack.
However, the former arrangement is such that as the width of the guide is fixed, and cannot be reduced to exactly that of the sheets in order to permit the same to received without incident, the desired effect has not been achieved. With the latter arrangement in order to adjust the width of the guide, a drive mechanism is necessary. This provision increases the bulk of the arrangement undesirably and further does not permit the mixing of different sheet sizes.
In connection with the fastening devices which staple the stack of sheets together, the stapler must be moved to a fastening position for the stapling operation and then back to its home or original position after the stapling is completed. An example of a mechanism for returning the stapler to its original or home position can be found in Japanese Patent Application Laid-Open No. 59-69346 (1984).
However, with this type of prior art arrangement the stapler must be moved a relatively large distance from its home position to its fastening one. As a result the layout of the finisher is rendered undesirably wide and prevents the achievement of a desirably compact arrangement.
A further problem comes in that the large distance through which the stapler must be moved requires a finite amount of time and slows the overall operation of the finisher.
It is an object of the present invention to provide a sheet finisher which overcomes the above mentioned prior art drawbacks and which features a compact construction.
It is another object of the present invention to provide a sheet finisher which includes a sheet folding device which has a simple and compact construction of transfer chutes and which is inexpensive to manufacture.
It is a further object of the present invention to provide a sheet finisher which includes a folded sheet discharging mechanism which increases the sheet accumulation capacity thereof without loss of sheet alignment capabilities.
It is still another object of the present invention to provide a sheet finisher which features a simple and compact construction and which simultaneously maintains highly acceptable alignment and accumulation characteristics.
It is a still further object of the present invention to provide a compact sheet finisher which is able to accurately compile sheets irrespective of their size.
It is another object of the present invention to provide a sheet finisher which features a compact construction and which accommodates the accumulation of a large amount of sheets without loss of alignment characteristics.
It is a further object of the present invention to provide a sheet finisher which includes an accommodation or storage arrangement which can assuredly unload stacks of sheets from the upper tray onto a lower one.
It is another object of the present invention to provide a sheet finisher which features a compact construction together with fastening arrangement which reduces the amount of time required for stapling the stacks of sheets together.
In order to achieve the above objects a first aspect of the invention features the provision of: first and second transfer guides, the first guide being arranged to receive sheet which is introduced in the finisher; a first a sheet direction switching means for selectively guiding the sheet into one of the first and second transfer guides; a temporary accommodation guide arranged to receive the leading ends of the sheet which is transferred through the first transfer guide; a third transfer guide arranged to extend from the outlet of the first guide to the outlet of the second guide; a first pair of press rollers disposed at the entrance of the third transfer guide and arranged to press a fold into the sheet which passes therebetween; first restricting means disposed in temporary accommodation guide for restricting the movement of the leading edge of the sheet; a second pair of press rollers disposed adjacent to the exits of the second and third transfer guides, the second pair of press rollers being arranged to press a fold into the sheet which passes therebetween; a second sheet direction switching means for selectively guiding the sheet which is transferred through the third transfer guide into one of the second transfer guide and the second pair of press rollers, the second sheet direction switching means being disposed at the exit of the third transfer guide; second restricting means disposed in the second transfer guide for restricting the movement of the leading edge of the sheet; a first pair of transfer rollers disposed in the first transfer guide; and a second pair of transfer rollers disposed in the third transfer guide.
In accordance with the first aspect of the invention, during the half folding mode the sheet which is transferred through the first transfer guide is introduced into the temporary accommodation guide to the degree wherein the mid portion of the sheet is induced to bow toward and be pressed by a first pair of press rollers in a manner to form a fold across the middle of the sheet. This half folded sheet is then transferred by way of the third transfer guide to the second pair of press rollers whereafter it is discharged.
On the other hand, during the Z folding mode, the movement of the leading edge of the sheet which is transferred from the first guide arrangement to the accommodation guide is restricted by the first restricting means at a 1/4 way position. Then, the 1/4 length portion thereof is induced to bow toward and sandwiched between the first pair of press rollers to form a crease.
Following this, the sheet is transferred through the third transfer guide and selectively guided in a manner which causes it to slide in the reverse direction into the second transfer guide. The second restricting means limits the entry into the second transfer guide to the degree that the mid portion of the sheet is induced to bow toward and be pressed between the second pair of press rollers. This produces a second fold in the middle of the sheet and the thus Z folded sheet is then discharged.
Further, in the case that sheet folding is not required the first switching means is set to guide the sheets into the second guide arrangement wherein they are passed through the second press roller pair and then discharged.
Therefore in accordance with the present invention, as the second guide arrangement functions as a guide for non-folded sheets and also acts as a temporary accommodation guide, it is possible to render the guide arrangement both simple and compact.
A second aspect of the present invention comprises means for producing a plurality of sheet folding modes including a Z folding mode; a pair of discharge rollers arranged to, discharge a sheet onto a tray; and sheet discharge angle control means for varying the angle at which the sheet is discharged by the pair of discharge rollers in accordance with a predetermined folding mode.
In accordance with the second aspect of the present invention, during the above mentioned predetermined folding mode, the angle at which sheet is discharged onto the tray is varied in a manner wherein, during the Z folding mode by way of example, if the angle at which the sheet is discharged is large even under the conditions wherein a plurality of sheets accumulate, the discharged sheet does not collide with the collected stack and the alignment and the stacking characteristics are simultaneously improved.
A third aspect of the present invention features a plurality of folding modes wherein the folding device includes a discharge roller pair which ejects sheets onto a tray, and which is constructed such that, in accordance with a predetermined folding mode, one portion of the lower surface or floor of the tray on which the discharged sheets are collected can be raised and lowered by a drive means so that the distance between the floor and the discharge rollers can be varied.
In accordance with the third aspect of the present invention, during the above mentioned sheet folding mode the raising and lowering of the floor portion changes the distance between the tray floor and the discharge device such that, during the non-folded sheet mode for example, the above mentioned portion of the floor is raised in a manner wherein the tendency for the sheet to float on the layer of air between the discharged sheet and those on top of the tray, is reduced in a manner which improves the alignment characteristics of the arrangement. On the other hand, during folding modes, the floor portion is lowered so that the number of sheets which can be accomodated increased. In this latter case, due to the folding, mass per unit area of the sheets is relatively large and the effect of the flotation force is essentially non-existent.
A fourth aspect of the present invention features a sheet finisher comprising: a tray, the tray being angled and having at least one upright side wall and a main or an inboard end wall having an aperture; discharge means for discharging a sheet onto the tray; sensing means for sensing the discharge of the sheet by the discharge means onto the tray; a friction roller for engaging the upper surface of the discharged sheet, the friction roller being arranged to rotate within a plane at a predetermined acute angle with respect to the main wall; drive means for driving the friction roller, the drive means including a flexible wire; and guide means for supporting the friction roller and responsive to the sensing means for guiding the friction roller from a home position out through the aperture in the main wall a predetermined time after the sensing means detects the discharge of the sheet, and for guiding the friction roller back to the home position after a predetermined time has lapsed.
In accordance with the fourth aspect of the present invention, a predetermined time after the sensing means detects the discharge of the sheet, the friction roller which is rotatably driven by the flexible wire, is guided out through the opening in the main wall until it assumes a sheet engaging position. The sheet is moved under the influence of the friction roller toward a top corner of the tray. As the plane of rotation of the friction roller defines a predetermined acute angle with respect to the main wall, the sheet is induced to abut against the main wall and one of the side walls and thus become neatly stacked in the corner of the tray. Following this, the friction roller is moved back from its sheet engaging position and returned to its home or original position.
With the the above described operation, it is possible to neatly position a predetermined number of sequentially discharged sheets.
A fifth aspect of the present invention features a sheet finisher which features: a sheet folding section; an upper tray onto which the sheets which are discharged from the folding section are collected; fastening means for fastening together a stack of sheets collected on the upper tray; a lower tray, the lower tray being inclined at a predetermined angle; means for dropping the fastened stack of sheets from the upper tray toward the lower tray; means for determining the number of sheets which have been discharged from the sheet folding section; and lower tray angle control means for changing the angle of the lower tray in response to the sheet number determining means indicating the sensing of a predetermined number of sheets.
In accordance with the fifth aspect of the present invention, when the count of the ejected sheets which have discharged onto the tray has reached the predetermined level, the angle of the lower tray is switched in a manner wherein the entry angle as taken along the vertical line to the upper sheet of the topmost stack, is increased and thus increases the amount of sheets which can be accommodated on the tray and obviates collisions between the stacked sheets and the pile which is being dropped theretoward.
A sixth aspect of the present invention features a sheet finisher comprising: a tray onto which sheets can be discharged and subsequently piled; a fastening device, the fastening device being operatively disposed with the upper tray for fastening the pile of sheets together; a lower tray, the lower tray receiving the fastened stack of sheets which are dropped from the upper one; escape means for permitting the fastened stack of sheets to be selectively slide off the upper tray and drop toward the lower one, the escape means comprising: a pivotal base wall member, the pivotal base wall member being pivotally mounted on a base side of the upper tray; a shutter arrangement which can be pivoted toward the bottom of said upper tray, and driving means for selectively pivoting the pivotal base wall member and the shutter arrangement.
In accordance with the sixth aspect of the invention, after the pile of sheets are fastened together, the pile is released from the upper tray by the pivoting of not only the base wall member for aligning the sheets but also the shutter arrangement toward the lower one under the control of the driving means and in a manner which is not influenced by friction between the stack of sheets and the tray nor by static electricity. Following the release of the stack of sheets the driving means returns the base wall member and the shutter arrangement to their original positions.
A seventh aspect of the present invention features a sheet finisher comprising: a tray onto which sheets can be discharged and piled, the tray being formed with a cut-out at a corner thereof; means for aligning the sheets which are discharged onto the tray with corner of the tray: tray support means for supporting the tray in a manner which permits it to be moved laterally from side to side; a stapler, the stapler being pivotally supported on a shaft; drive means for pivoting the stapler through a predetermined angle toward the cut-out; means for moving synchronously the tray and the stapler; in such a way that the cut-out and an operational position of the stapler mutually closes with each other.
In accordance with the seventh aspect of the invention when the alignment of the sheets with the cut-out portion of the tray which is supported slidably on the tray support means is completed, the tray and the stapler are moved synchronously in such a way that the cut-out portion and an operational position of the stapler mutually closes with each other. When the cut-out portion of the tray and the stapler are suitably located with respect to one and other the stapler is energized to fasten the sheets together. Upon completion of fastening the tray and the stapler are returned to their original positions, respectively.
The above mentioned combination of the laterally movable tray and the pivotal stapler and the associated driving means for the same, is such as to permit the overall construction of the finisher to be rendered compact.
The above and other objects, effects, features and advantages of the present invention will become more apparent from the following description of embodiments thereof taken in conjunction with the accompanying drawings .